Multilayer structure with embedded multilayer electronics

ABSTRACT

An integrated multilayer assembly for an electronic device includes a first substrate film configured to accommodate electrical features on at least first side thereof, said first substrate film having the first side and a substantially opposing second side, a second substrate film configured to accommodate electrical features on at least first side thereof, said second substrate film having the first side and a substantially opposing second side, the first sides of the first and second substrate films being configured to face each other, at least one electrical feature on the first side of the first substrate film, at least one other electrical feature on the first side of the second substrate film, and a molded plastic layer between the first and second substrate films at least partially embedding the electrical features on the first sides thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/156,008 filed Oct. 10, 2018, which is a continuation of PCTInternational Application No. PCT/FI2017/050260 filed Apr. 11, 2017,which claims priority to U.S. Provisional Patent Application No.62/321,771, filed Apr. 13, 2016, the disclosure of each of theseapplications is expressly incorporated herein by reference in theirentirety.

FIELD OF THE INVENTION

Generally the present invention pertains to multilayer structures inconnection with electronics, associated devices, and related methods ofmanufacture. In particular, however not exclusively, the presentinvention concerns provision of functional elements such as electronicsin the multilayer stack.

BACKGROUND

Generally there exists a variety of different stacked assemblies andstructures in the context of e.g. electronics and electronic productssuch as various electronic devices.

The motivation behind stacking elements in a common structure may be asdiverse as the related use contexts. Relatively often size savings,weight savings, cost savings, usability benefits, or just efficientintegration of components in terms of e.g. the manufacturing process orlogistics is sought for when the resulting optimized solution ultimatelyexhibits a multilayer nature. In turn, the associated use scenarios mayrelate to product packages or food casings, visual design of devicehousings, wearable electronics, personal electronic devices, displays,detectors or sensors, vehicle interiors, antennae, labels, vehicle andparticularly automotive electronics, etc.

Electronics such as electronic components, ICs (integrated circuit) andconductors may be generally provided onto a substrate element by aplurality of different techniques. For example, ready-made electronicssuch as various surface mount devices (SMD) may be mounted on asubstrate surface that ultimately forms an inner or outer interfacelayer of a multilayer structure. Additionally, technologies fallingunder the term “printed electronics” may be applied to actually produceelectronics directly and additively to the associated substrate. Theterm “printed” refers in this context to various printing techniquescapable of producing electronics/electrical elements from the printedmatter, including but not limited to screen printing, flexography, andinkjet printing, through a substantially additive printing process. Theused substrates may be flexible and printed materials organic, which ishowever, not necessarily always the case.

A substrate such as a plastic substrate film, may be subjected toprocessing, e.g. (thermo)forming or molding. Indeed, using e.g.injection molding a plastic layer may be provided on the film,potentially then embedding a number of elements such as electroniccomponents present on the film. The plastic layer may have differentmechanical, optical, electrical, electrical, etc. properties. Theobtained multilayer, or stacked, structure may be configured for avariety of purposes depending on the included features, such aselectronics, and the intended use scenario and related use environment.It may, for instance, comprise one or more connecting features such asfluke type protrusions for coupling with compatible recesses of a hostelement or vice versa.

As the electronics may not, however, always be a critical or solefeature of highest priority or of most importance in the associatedproduct, and they may actually be considered supplementary, optionalfeatures only, the design and implementation of features providing thedesired electrical effect shall be carefully executed. Weight and sizerequirements, elevated power consumption, additional designconsiderations, new process steps, and generally increased overallcomplexity of the manufacturing phase and the resulting product are allexamples of numerous drawbacks easily becoming materialized as a sideeffect of adopting various electronic features in the target solution.

In the light of the foregoing, in many real-life manufacturing scenariosfitting all the desired electronic or generally electrical features on asubstrate film has turned out very challenging if not impossible due tothe limited surface area available for mounting or producing thefeatures thereon and e.g. the necessary physical separation someelements should in any case have to function in optimal or even propermanner. Further, in some applications placing several features on acommon substrate either adjacent to each other or at a distance issub-optimum in any case as the resulting rather limited spatialseparation of the features reduces the achievable spatial resolution ofthe implemented functionality, which may be a sensing functionality, forinstance.

SUMMARY

The objective of the present invention is to at least alleviate one ormore of the above drawbacks associated with the existing solutions inthe context of various devices or other host elements that are to beprovided with embedded electrical, such as electronic, features.

The objective is achieved with the embodiments of a multilayer assemblyand a related method of manufacture in accordance with the presentinvention.

According to one embodiment of the present invention, an integratedmultilayer assembly for an electronic device comprises

a preferably flexible first substrate film configured to accommodateelectrical features, such as conductive traces and electroniccomponents, e.g. SMDs (surface-mount device), on at least first sidethereof, said first substrate film having the first side and asubstantially opposing second side,

a preferably flexible second substrate film configured to accommodateelectrical features, such as conductive traces and electronic componentson at least first side thereof, said second substrate film having thefirst side and a substantially opposing second side, the first sides ofthe first and second substrate films being configured to face eachother,

at least one electrical feature on the first side of the first substratefilm,

at least one other electrical feature on the first side of the secondsubstrate film, and

a molded plastic layer between the first and second substrate films andat least partially embedding the electrical features on the first sidesthereof.

The films may be adjacent to and contact the molded layer. Preferablythe layer has been molded in between the films so that the films and thelayer are attached together and establish the stacked multilayerassembly.

In one embodiment at least one aforesaid electrical feature on either orboth substrate films comprises or defines an electrode for sensing. Theone or more electrodes may be utilized as a part of a capacitive gestureand/or touch sensing arrangement, for example. Thus, at least twostacked and optionally overlapping (in the thickness direction of theassembly) electrodes, preferably at least one on each film, mayconstitute at least part of an electrode structure for the purpose ofdetecting e.g. touch or 3d gestures upon or more generally in thevicinity of the multilayer assembly.

In one, either supplementary or alternative, embodiment, either or bothof the substrate films is formed, e.g. thermoformed, to a desired3d-shape. Forming may optionally take place after locating at least someof the electrical features such as electronic components on the films.Originally the films may be planar and at least some of the features maybe positioned to selected locations thereon prior to shaping. Preferablythe locations are selected so that the subsequent forming does notdirect excessive stress thereto to avoid breakage of thealready-positioned features or their mutual connections such as traceson the substrate.

In some embodiments, the features on either or both films may includelight sources or light detectors. For example, a number of LEDs may bepositioned on the film(s). Alternatively or additionally light detectorssuch as photodiodes or phototransistors or photovoltaic devices may beincluded on the film(s) or generally within the assembly.

The plastic layer may contain optically at least translucent, optionallytransparent, material having regard to a predetermined frequency orfrequency band, optionally visible light. The layer may establish alightguide layer for transmitting light e.g. from an embedded lightsource to the environment or from the environment or embedded lightsource to an embedded detector.

In some embodiments, the assembly may further contain at least oneadditional layer, such as protective, aesthetic and/or connection layer,on the second surface(s) of either or both films.

The first substrate film may be optically substantially opaque,translucent or transparent having regard to a predetermined frequency orfrequency band. The film may exhibit a selected color or selectedcolors. Frequencies emitted by the embedded or external light sources(and potentially captured by the optional light detectors) may beabsorbed, reflected or transmitted by the substrate film. Similarconsiderations apply to the second substrate film.

Yet, either or both of the substrate films may be provided withfunctional features such as electrical or particularly electronicfeatures on the second side thereof.

In some embodiments, either or both of the substrate films may includegraphics such as symbols, patterns, text, figures, etc. Such may beprovided using IML/IMD (in-mold labeling, in-mold decoration)technology.

The additional layer(s) may be directly produced or laminated onto theaggregate of the substrate films and molded plastic layer therebetween.Lamination may involve application of heat, pressure and/or adhesive.

According to a further embodiment, a method of establishing anintegrated multilayer assembly for an electronic device comprises

obtaining a preferably flexible first substrate film configured toaccommodate electrical features, such as conductive traces andelectronic components, e.g. SMDs (surface-mount device), on at leastfirst side thereof, said first substrate film having the first side anda substantially opposing second side,

obtaining a preferably flexible second substrate film configured toaccommodate electrical features, such as conductive traces andelectronic components on at least first side thereof, said secondsubstrate film having the first side and a substantially opposing secondside,

providing at least one electrical feature on the first side of the firstsubstrate film,

providing at least one other electrical feature on the first side of thesecond substrate film,

arranging the first and second substrate films in a mold, preferably onefilm per mold half, so that the first sides thereof are configured toface each other in substantially spaced relation, and

molding a plastic layer between the first and second substrate films andat least partially embedding the electrical features on the first sidesthereof.

The molding method is preferably injection molding. The substrate filmsalready provided with further features such as electronics may beutilized as inserts.

Different considerations presented herein concerning the embodiments ofthe assembly may be flexibly applied to the embodiments of the methodmutatis mutandis, and vice versa, as being appreciated by a skilledperson.

The utility of the present invention arises from a plurality of issuesdepending on the embodiment.

The obtained multilayer structure may be generally kept relatively lightand compact, e.g. thin, while it remains sturdy and protects theembedded functional features and exhibits e.g. a desired appearance interms of dimensions, shape, colors and/or graphical patterns.

Provision of two substrate films and particularly electrical featuressuch as traces, electrodes, electronic components and/or generallyelements on both of them yields significant benefits in terms ofinstallation space or surface area available and overall spatialconfigurability. For example, one or more electrode pads or electrodeareas established from e.g. conductive printed material may be providedto both films in a spatially desired fashion (e.g. at least partiallyoverlapping in the thickness direction of the assembly, i.e. in thedirection proceeding through the layers of assembly), which enables, incooperative combination, accurate capacitive sensing of user input orgenerally gestures, e.g. 3d-gestures, upon the assembly. Both touch andcontactless gestures may be detected. Alternatively, one or moreelectrodes or generally sensing elements for detecting e.g. touch couldbe provided on the front (when in use) substrate film only to facilitatetouch detection over solutions wherein the back film farther away fromthe touch location on the assembly surface was solely provided with asensing element.

The used thermoplastic molding material may be optimized for variouspurposes including securing electronics in view of the molding process.Yet, the molded material optionally together with other used materialsmay be configured to protect the embedded features such as electronicsfrom e.g. environmental conditions such as moisture, heat, cold, dirt,shocks, etc.

In case of optical applications, the optical coupling between theembedded optoelectronics such as light sources or detectors and themolded lightguide material may be strong with low loss and withoutsubstantial artifacts. Relative simplicity of the associatedmanufacturing process yields benefits own its own with reference to e.g.the related rather tolerable device and material costs, space, processtime, logistic and storage requirements.

Yet, the assembly may exhibit a selected appearance or e.g. tactile feelto the viewer such as operator by the configuration of surface graphics,embedded graphics (may still be visible e.g. through the window),surface materials with different surface profiles, general shape, etc.

The embedded features may be mounted or directly produced onto thesubstrate film(s) by printing. Preferred printing techniques areadditive (printed electronics technology) and include e.g. screenprinting, flexography and ink jetting.

The expression “a number of” may herein refer to any positive integerstarting from one (1).

The expression “a plurality of” may refer to any positive integerstarting from two (2), respectively.

The ordinal numbers such as “first” and “second” are herein used todistinguish one element from other element, and not to speciallyprioritize or order them, if not otherwise explicitly stated.

The terms “film” and “foil” are herein used generally interchangeably,unless otherwise explicitly indicated.

Different embodiments of the present invention are disclosed in theattached dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Next the present invention will be described in greater detail withreference to the accompanying drawings, in which:

FIG. 1 illustrates one embodiment of a multilayer assembly in accordancewith the present invention.

FIG. 2 is a cross-sectional side view of an embodiment of a multilayerstructure in accordance with the present invention.

FIG. 3 illustrates conceptually one embodiment of a manufacturingprocess for acquiring the multilayer assembly of the present inventionand related elements of the assembly.

FIG. 4 is a flow diagram disclosing an embodiment of a method inaccordance with the present invention.

DETAILED DESCRIPTION

In various embodiments, either or both substrate films may contain atleast one window defined by an opening, such as a through-hole, flap orcut, in the associated material layer.

The window(s) may optionally contain fill material different from thematerial of the film. The material is optionally optically translucentor transparent having regard to selected, e.g. visible, wavelength(s),optionally glass or plastic, such as glazing. It may define opticallyfunctional element such as a lens, prism or other refractive element,and/or a diffractive element, for example.

The window(s) may exhibit a desired indicative and/or decorative shape,such as at least partial shape of a text, number, symbol, graphicalpattern, and/or figure. Yet, the window material, when applicable, maybe of selected color.

In various embodiments, the material of the molded layer may establishat least part of the window filling. The material may define e.g. aprotrusion from the waveguide layer that is accommodated in the windowdefined by the substrate film and optionally potential further adjacentlayers. The molded material may in some embodiments also establish atleast a part of the exterior (top) surface of the assembly.

In various embodiments, the assembly may contain further films orgenerally layers in addition to the molded material and substrate filmson either or both sides thereof.

E.g. cover layer may be provided by at least one cover element such as afilm or board, or deposited coating, on either substrate film. The coverlayer may optionally also contain a window for enabling e.g. lightemitted by the embedded light sources of the assembly to pass through tothe environment or external light to pass into the assembly, e.g. withinthe molded material. The window may be aligned and at least partiallyoverlapping with a window of the underlying substrate layer. It may beof same or different size.

The material(s) of the cover may include plastic, glass, leather,textile, organic or generally fibrous material, for example. In someembodiments, the material may be substantially translucent ortransparent having regard e.g. to the wavelengths emitted by externallight sources and/or internal light sources of the assembly. In someother embodiments, it may be substantially opaque. The cover may havee.g. rubber or rubberous surface. The surface material and topology(surface forms) may be optimized to provide desired feel and/oraesthetic properties in addition to or instead of e.g. insulation (e.g.moisture and/or thermal) or dampening property. The cover layer may beflexible, elastic or stiff/rigid.

The cover layer may protect the assembly and/or facilitate itsattachment to a host device, for instance, if the assembly is notsecured to the host via either substrate film. The cover layer or insome scenarios, directly substrate film(s), may thus contain attachingfeatures such as adhesive material and/or mechanical fixing structure(s)e.g. in the form of boss/base, clip, hook, recess, etc. for the purpose.

Thus, depending on the used layer materials, their thicknesses, and e.g.embedded elements, the overall assembly may be generally flexible orrigid/stiff.

In various embodiments, the substrate films may contain plastic, metal,glass, leather, textile, organic and/or fibrous material (e.g. paper orcardboard). Preferably, the substrate films are or at least containelectrically insulating (dielectric) material. The substrate films maybe mutually of similar or different configuration as to the usedmaterials, their optical transparency, flexibility, hosted features suchas electronics, layer thicknesses and/or shapes, for example.

The substrate films may be optically opaque, translucent or transparenthaving regard to selected wavelength(s). The light emitted by externalor internal light sources of the assembly and later incident on thesubstrate may be capable of being at least partially absorbed by orpenetrating (transmitting) through either or both substrate filmsdepending on the used materials, respective refractive indices andgeneral configuration, e.g. geometry and surface topology, of thearrangement and elements thereof. However, the substrate films may be atleast locally reflective and contain reflective (surface) material e.g.in the form of coating or more thoroughly.

In various embodiments, the molded plastic layer may be opticallysubstantially opaque, translucent or transparent having regard to theselected wavelength(s), e.g. of visible light. In some embodiments, themolded layer may be configured to act as a lightguide. It may transportlight emitted by the internal light sources of the assembly, optionallyprovided on the substrate film(s) and at least partially embedded in themolded material, and/or external light.

In various embodiments, the substrate has been formed, preferablythrough thermoforming such as pressure forming, vacuum forming orhydroforming, to a desired substantially three-dimensional (non-planar),e.g. curved, angular or undulating, shape relative to its own thicknessprior to or upon the provision of e.g. molded layer thereon. Electricalfeatures, such as electronics in the form of printed electronics and/ormounted components, may have been already provided on the substrateprior to forming. The resulting 3d-shape could be several times thickerthan the initial film. Additionally or alternatively, such features mayhave been provided to the substrate subsequent to forming.

The multilayer assembly may be generally substantially planar or flat.The order of magnitude of the width and length of the assembly may thusbe different from the height (the direction in which the layers arestacked), i.e. ‘thickness’, which may be considerably smaller. Forexample, the thickness may be only a few millimeters or less whereas thewidth and length may be several centimeters or more, even considerablymore depending on the embodiment. The thickness may be constant or itmay vary considering e.g. the general shape of a discuss that the shapeof the assembly may in some embodiments generally conform to.

In some embodiments, instead of or in addition to light sources, anumber of light receivers or detectors, such as photodiodes,phototransistors, other suitable photoelectric elements, or e.g.photovoltaic elements (e.g. solar cell) are provided on the substratefilm(s). They may be at least partially embedded through molding insidethe established plastic layer. These elements are configured to captureor generally sense the light received through the substrate(s) or e.g.aforesaid window(s) and/or emitted by the internal light sources andpropagated within the plastic lightguide layer. Sensing data may beutilized in adjusting the light sources, for example.

In various embodiments, the electrical features included in theassembly, as provided on the substrate film and/or on further layer(s)or element(s) thereof, may generally comprise at least one elementselected from the group consisting of: conductive trace, printedconductive trace, contact pad, component, integrated circuit (chip),processing unit, memory, communication unit, transceiver, transmitter,receiver, signal processor, microcontroller, battery, light emittingdevice, light sensing device, photodiode, connector, electricalconnector, optical connector, diode, OLED (Organic LED), printedelectronic component, sensor, force sensor, antenna, accelerometer,gyroscope, capacitive switch or sensor, electrode, sensor electrode,printed electrode, printed sensor electrode, and photovoltaic cell. Thefeatures may be printed by means of printed electronics technology (e.g.screen printing or ink jetting, or other additive methods) and/ormounted. The features may be at least partially embedded e.g. in themolded lightguide layer or between different layers. Some features suchas connectors, which may be arranged to supply power to the assembly,for instance, may be at least partially exposed to the environment ofthe assembly.

As alluded hereinbefore, the cover layer(s), associated potential windowfill material(s), substrate films, molded layer and/or other elements ofthe assembly may have been provided with visually distinguishable,decorative/aesthetic and/or informative, features such as graphicalpattern and/or color thereon or therein. The features may have beenembedded in the assembly below the exterior surfaces thereof and/orprovided on the exterior surface thereof. Accordingly, IML (in-moldlabeling)/IMD (in-mold decoration) technique is applicable formanufacturing these features.

In various embodiments, the used mold may incorporate surface shapesthat establish corresponding mirror features thereof in the moldedplastic layer. The shapes/features may include e.g. a protrusion,grating, boss, boss-base, recess, groove, ridge, hole, or a cut.

With reference to the attached figures, FIG. 1 illustrates at 100 oneembodiment of a multilayer assembly in accordance with the presentinvention, in particular exterior thereof.

The depicted, merely exemplary, assembly 100 is generally of somewhatflat or planar discuss shape with low side walls, if any. The exteriorsurface of the assembly 100 is at least partially defined by a substratefilm 106 or optional cover layer(s) 108 thereon. Optionally asubstantially transparent or at least translucent, in this examplecircular, window 116A may be free from material or contain a circular,substantially planar plate of transparent or translucent material, e.g.plastic or glass.

A person skilled in the art appreciates the fact the optimum shape maybe determined case-specifically based on optical, dimensional (size) andaesthetic objectives.

In other feasible embodiments, the assembly 100 and related elementscould bear more three-dimensional shape thus having also considerablethickness or ‘height’.

The shown assembly 100 has strong (circular) symmetry around itsthickness/height axis but in some other embodiments the assembly or atleast one or more of its components bear different symmetry orsubstantially no symmetry (unsymmetrical) at all.

FIG. 2 shows, via a cross-sectional side view, an embodiment 200 of amultilayer assembly according to the present invention. This mainlyconceptual representation may thus cover e.g. the embodiment of FIG. 1and various other embodiments. Having regard to FIG. 1, the view couldhave been taken along line A-A, for instance. FIG. 3 illustrates, at300, essentially the same or similar embodiment especially from thestandpoint of the manufacturing process and layered construction. InFIG. 3, the illustrated layer thicknesses are only exemplary but mayalso reflect a real-life scenario in terms of relative thicknesses. Forinstance, either or both substrates 106, 202 may be of film type (withe.g. about 0.1 millimetre thickness) while e.g. the molded layer 204 maybe substantially thicker, e.g. one or few millimetres, or more.

The substrates 106, 202 have been provided with elements such aselectrically conductive traces (conductors) 210, electrodes 214A, 214Belectronic components 212, 214 such as light sources 214, lightreceivers/sensors, integrated circuits, etc. as mentioned hereinbeforeat least on first side thereof (the top/upper surface in the figure).Additionally, such elements 314A could be provided on bothsides/surfaces thereof and/or embedded therein, optionally at leastpartly after molding of layer 204 of preferably thermoplastic material.

The substrates 106, 202 may, besides structurally via the molded layer204, be also functionally, e.g. electrically, connected together toenable e.g. signalling and/or current provision between them.

The connection 230 between the substrates 106, 202 may be realizedthrough the use of conductive elements such as a metal pin, flexcircuit, etc. In some embodiments, also wireless connection (e.g. rf oroptical) may be applied.

The (wired) connection 230 may be established subsequent to molding orbefore that using e.g. applicable mold features to protect theconnecting element during molding. Alternatively or additionally, e.g. alead-through may be established for the connecting element duringmolding by appropriate mold feature such as a column preventing thematerial 204 from flowing to the space occupied by it.

As one other alternative or supplementary option, the substrates 106,202 may be e.g. electrically connected together at the edges, optionallyvia electrical wiring, flex circuit or other conductors, which mayenable omitting e.g. the removal of molded material 204 for theconnection afterwards from a more central area of the establishedmultilayer stack, or arranging a specific mold feature such as a columnfor creating a necessary lead-through.

As a further option, the molded material 204 may be machined such asdrilled or otherwise processed to arrange a lead-through therein for theconnection and related conductive element(s).

Power supply and/or communication connection to either substrate 106,202 having regard to external electronics or e.g. host deviceelectronics may be arranged generally in a similar fashion, e.g. viaside contacts provided at the edge.

In some applications, instead of molding the layer 204 it could beprovided otherwise with reference to e.g. a ready-made elementpreferably containing the necessary surface forms such as recesses forreceiving and accommodating at least part of the electronics 212, 214protruding from the first, upper, surface of the substrate 204.

The substrate 106 may be laminated to or produced on top of the moldedlayer 204. It 106 may contain at least one window 116, or in someembodiments, a plurality of windows as discussed hereinbefore, forenabling e.g. the light emitted by the light source 214 to betransmitted through towards the environment and/or other type ofinteraction with the environment optionally for sensing purposes. Insome other embodiments, the substrate 202 may additionally oralternatively contain at least one such window (not explicitlyrepresented in the figure for clarity reasons).

The window 116, layer 204 and light source 214 (and/or other relevantelements, such as light detectors/sensors) may have been configured interms of e.g. mutual position, materials, dimensions and shape such thatthe light emitted by the sources 214, propagating within the layer 204and incident on the window(s) 116 passes through the window(s) 116 atleast having regard to selected incident angles.

Yet, the configuration may optionally be such that the light sourcesand/or other internal elements, such as additional electronics, remainhidden from the viewer substantially completely or at least within aselected inspection angle relative to a reference such as the surfacenormal of the assembly (i.e. the surface normal of the windowfill/masking layer 106 or of potential top layer 108, or even of layer204 in cases where there's no window fill material). The magnitude ofthe associated critical angle may be e.g. about 10, 15, 20, 30, 40, 45,50, 60 or more in degrees. In some other embodiments, the referencerelative to which and potentially around which, the above viewing angleis defined could differ from the above surface normal and may thereforebe e.g. a line at a certain angle such as 45 deg angle therefrom.

At least one cover/top layer 108 may be optionally provided and arrangedwith a window 116C that may be aligned relative to the window of thesubstrate 106 so that the light exits the overall assembly, not just themolded layer 204 and substrate 106, to desired extent. For example, thewindows 116, 116C may be substantially superimposed along thethickness/height direction of the assembly.

At least one bottom layer 218 may be optionally provided below thesubstrate 202 on the side opposite to the molded layer 204. The bottomlayer 218 may have aesthetic (provided by e.g. graphics, surface forms,color, etc.), tactile (e.g. through surface forms, material selection),protective (material properties, thickness, flexibility/stiffness,hardness, insulation properties, etc.), connective/fixing (e.g.stickiness, adhesion, mechanical such as protrusion, recess, hook,velcro), conductive (electrically conductive material, traces,leads/wires or other conductors) and/or other function.

In some embodiments, the bottom layer(s) 218 are omitted and theassembly 200 is attached via the substrate 202 to the host device orother host element 218. As a further alternative, the assembly 200 maybe of stand-alone element or device type or attach to the host or otherelement via other surface (e.g. via side wall(s)/edges or top surface).

In some embodiments, the assembly 200 forms at least part of a casing orcover of the host device/element. The assembly may be shaped accordinglyto exhibit a generally convex, hollow, receptacle and/or containershape, for example.

The assembly 200 may be configured so as to effectuate internalreflection, preferably total internal reflection based propagation oflight within the molded layer 204 acting as a lightguide. The reflectiontype propagation of light instead of unwanted absorption/leaking may beenhanced through using suitable materials. The layer 204 may have e.g.higher refractive index than the adjacent substrates 106, 202, bottomlayer/host element surface/protection layer 218 and/or associatedreflector. Yet, the location and geometry of the lightguide layer 204relative to the light sources 214, such as top or side emitting LEDs,may be configured such that the light generally arrives at the materialinterfaces with angles greater than the related critical angle to ensureinternal reflections as being understood by a person skilled in the art.

In some embodiments, e.g. either or both substrates 106, 202 and moldedlayer 204 may have substantially similar optical properties in terms ofe.g. refractive index. The interface between the elements may be thenconsidered transparent or substantially non-existing relative to theincident light and e.g. total internal reflection based propagationthereof within the then functional combination of layer 204 andsubstrate 106, 202.

Having regard to the potential illumination and/or light propagationfeatures of the assembly 200, one general objective may be in providinguniform lighting, or uniform ‘brightness’ distribution, via the window116 towards the environment without hotspots as mentioned hereinearlier.The directivity of the light (is it e.g. collimated or diffuse) may bedetermined case-specifically as well. For example, diffuse/collimatinglens or other feature could be implemented by the properly shaped windowfillings 116, 116C and/or other elements of the assembly. Embeddedreflecting/mirroring features such as plates, films, or layer surfacescould be utilized for similar purpose.

In addition to the light projected/emitted by the assembly 200(originated by the light sources 214) the perceived illuminationuniformity of the surface also depends on the uniformity of thereflected external light.

Regarding the reflection properties of the window 116, 116C relative toexternal light arriving thereat from the environment of the assembly200, the associated filling (or other element, such as the layer 204, ofthe assembly receiving the external light if there's no window fillingin the case of e.g. through-hole type window) may incorporate an outersurface facing the environment. That surface is preferably ideally ormaximally diffusive to reflect such incident light equally in everydirection. This kind of diffusion property may be achieved by elevatingsurface roughness, for example.

To obtain the desired illumination characteristics such as uniformity,in some embodiments the assembly 200 may be configured in terms ofilluminance of the window 116, 116C or the other element defining atleast part of the exterior surface outcoupling the internallytransmitted light to the environment and potentially reflecting externallight. Constant illuminance of the window 116, 116C from the underlyinglayer 204 may be thus considered as one potential design objective.

Additionally or alternatively, luminance and/or luminous intensity ofthe window 116, 116C or the other element may be configured to be atleast sufficiently (the appropriate level of sufficiency shall benaturally determined embodiment-specifically by a skilled person)constant.

Generally, the illumination properties of the assembly 200 andparticularly e.g. the window 116, 116C thereof may indeed be determinedby the combination of the used elements related materials, their mutualpositioning, as well as dimensions and shape. The shape may cover bothsurface topology and overall geometry.

FIG. 4 includes a flow diagram 400 disclosing an embodiment of a methodin accordance with the present invention.

At the beginning of the method for manufacturing the multilayerstructure, a start-up phase 402 may be executed. During start-up 402,the necessary tasks such as material, component and tools selection,acquisition, calibration and other configuration activities may takeplace. Specific care must be taken that the individual elements andmaterial selections work together and survive the selected manufacturingand installation process, which is naturally preferably checked up-fronton the basis of the manufacturing process specifications and componentdata sheets, or by investigating and testing the produced prototypes,for example. The used equipment such as molding/IMD (in-molddecoration), lamination, bonding, thermoforming, cutting, drillingand/or printing equipment, among others, may be thus ramped up tooperational status at this stage. Mold(s) may be prepared with necessarysurface forms, etc.

At 404, preferably flexible substrate films and/or potentially otherpreferably planar substrate elements for accommodating electronics areobtained. A ready-made element of substrate material, e.g. a roll ofplastic film, may be acquired. In some embodiments the substrate filmitself may be first produced in-house by molding, extrusion or othermethods from the desired source material(s). Optionally, the substratefilm is processed. It may be, for example, coated, cut and/or providedwith openings, notches, recesses, cuts, etc. as contemplatedhereinbefore. The initial and/or resulting film may bear e.g.rectangular, square or circular shape. The substrate may be opaque,translucent or substantially transparent having regard to selectedwavelengths of light or generally electromagnetic radiation, such as theoperation wavelengths of the light sources or detectors to be providedthereon.

At 406, a number of conductive elements or traces defining e.g.conductor lines of a desired circuit pattern or circuit design,electrodes, contact pads (or other contact areas), etc. for electricallycoupling electronic components, are provided on either or both substratefilms, preferably by one or more techniques of printed electronics withreference to related additive technologies. For example, screen, inkjet,flexographic, gravure or offset lithographic printing may be utilized.Also further actions cultivating the film(s) involving e.g. printing ofgraphics, visual indicators, etc. may take place here.

At 408, a number of electronic elements or components, such asprocessing elements, communication elements, memory elements, sensingelements, and/or light sources such as LEDs may be provided on either orboth substrate films and related surfaces. In practice, e.g. ready-madecomponents such as various SMDs may be attached to the selected contactareas by solder and/or adhesives. Alternatively or additionally, printedelectronics technology may be applied to actually manufacture at leastpart of the components, such as OLEDs, directly onto the film(s).

In some embodiments, either or both substrate films may be formed toexhibit a desired 3d-shape (a substantially non-planar shape),preferably through thermoforming 418 such as vacuum or pressure forming.The substrate containing thermoformable material may be shaped to betterfit the host device or use scenario. Additionally or alternatively,thermoforming could even take place after molding 410 in case thealready-established multilayer stack is designed to survive suchprocessing. Having regard to forming techniques, e.g. pressure formingmay be applied to provide the substrate with very precise, sharpdetails. Pressure forming may be generally preferred when the substratelacks (through-)holes that could enable undesired flow and resultingpressure drop via them.

In some embodiments, a number of sub-assemblies ofelectronics/sub-substrates may be provided as such to either or bothsubstrates at 409 and secured by adhesive, for instance.

At 410, at least one thermoplastic layer optionally establishing alightguide for the light emitted by the light sources and/or external(e.g. ambient) light is provided, preferably through molding, upon thefirst side of at least one of the substrate films and at least part ofthe electrical features thereon, such as traces and a number ofelectronic components. Preferably the light sources and/or otherfeatures are at least partially embedded within the molded material. Inpractice, one or both substrate films may be used as an insert in aninjection molding process. The first side and associated surface of thesubstrate element may be, in some embodiments, left with one or moreareas, such as borders, free from the molded plastics. In someembodiments, both sides of a substrate film may be provided with moldedlayer(s). The thermoplastic material used may be opaque or at leasttranslucent. It may exhibit at least one color.

In some embodiments, both substrate films may be first inserted in theirown mold halves so that the plastic layer is injected between themduring actual molding. Preferably the films are located in the mold(halves) with substantially, if not completely, spaced relation to eachother, i.e. with some space between them to be then occupied by theinjected thermoplastic material.

Substantially spaced relation may still in some embodiments refer toscenarios wherein local areas of both films, e.g. edge areas, are incontact with each other. E.g. the afore-reviewed discuss shape may bethen obtained as outcome with film edges connected or at least close toeach other while the remaining portions, e.g. central portions, of thefilms are farther away from each other as separated by the moldedplastics.

The plastic may be injected via one or more locations e.g. from theside(s) of the film(s). Thus e.g. edge injection and/or hole injection(plastic injection between the films through one or more holes in thefilm(s)) may be applied. Alternatively, one of the substrate films couldbe attached to an already-formed aggregate of the other substrate filmand molded plastic layer afterwards by a suitable lamination technique.

Either substrate film could be provided with at least one hole for theafore-discussed window(s). The hole may result from cutting, drilling,carving, stamping or etching operation, for instance. During molding,the thermoplastic molding material may then enter the hole from eitheror both sides, optionally also proceeding to the other side of the film,and establish at least part of the window fill for at least theconcerned film.

In some embodiments, there is no through-hole ready in a substrate filmprior to the molding. The film may still optionally have e.g. a thinnedor otherwise weakened (formed using e.g. one of the abovementionedoperations) spot at the target location of the window to facilitatewindow formation during molding due to the pressure of the moldedmaterial. In some embodiments, the mold surface contacting the otherfilm may have a surface feature such as a recess, perforated area, flapor pinhole thereon corresponding to the target location of the window inthe film, which may facilitate forming and/or filling the window duringmolding. The feature thus matching and facing the desired area of thewindow in the film may further enable the molded material to flow viathe window to the other side (i.e. mold/exterior side) of the film.

Having regard to few examples of the applicable material selections, thesubstrate film and/or potential further film(s) or material layers maysubstantially consist of or comprise at least one material selected fromthe group consisting of: polymer, thermoplastic material, PMMA(Polymethyl methacrylate), Poly Carbonate (PC), polyimide, a copolymerof Methyl Methacrylate and Styrene (MS resin), glass, organic material,fibrous material, Polyethylene Terephthalate (PET), and metal.

The feasible molding methods include e.g. injection molding. In case ofseveral plastic materials, they may be molded using a two-shot orgenerally multi-shot molding method. A molding machine with multiplemolding units may be utilized. Alternatively, multiple machines or asingle re-configurable machine could be used for sequentially providingseveral materials. Optionally, several overmolding-applicable materialsmay be utilized to establish one or more molded layers, e.g. adjacentlayers between the substrate films.

The (thermo)plastic material used to establish the molded layer(s)comprises optically substantially opaque, transparent or translucentmaterial having regard to selected wavelengths enabling e.g. lightemitted by the embedded light sources and/or external (e.g. ambient)light, such as visible light, to pass through it with negligible loss.The sufficient transmittance of the material at selected wavelengths maybe about 60%, 70%, 75%, 85%, 90% or 95% or higher, for example,depending on the embodiment.

The plastic layer(s) provided by e.g. the aforementioned moldingprocedure or heat, pressure and/or adhesive based lamination to theassembly may generally incorporate e.g. elastomeric resin. In moredetail, the layer(s) may include one or more thermoplastic materialsthat include at least one material selected from the group consistingof: PC, PMMA, ABS (Acrylonitrile butadiene styrene), PET, nylon (PA,polyamide), polypropylene (PP), polystyrene (GPPS), and MS resin.

At 412, further layer(s) may be optionally provided to the assembly.Provision may include direct manufacturing through e.g. molding,deposition/other coating method, and attaching. A window-defining cut orhole may be optionally provided in the masking and potential furtherlayers by drilling, carving, sawing, etching, cutting (e.g. with laseror mechanical blade), or using any other feasible processing method asbeing understood by a person skilled in the art. Alternatively, thelayer(s) may be produced with ready-made window feature through molding,for example.

Regarding the resulting overall thickness of the obtained stackedstructure, it heavily depends on the used materials and related minimummaterial thicknesses providing the necessary strength in view of themanufacturing and subsequent use. These aspects have to be considered oncase-by-case basis. For example, the overall thickness of the structurecould be about 1 mm, but considerably thicker or thinner embodiments arealso feasible.

Item 414 refers to possible post-processing tasks and attachment to ahost device or element.

At 416, method execution is ended.

The scope of the present invention is determined by the attached claimstogether with the equivalents thereof. A person skilled in the art willappreciate the fact that the disclosed embodiments were constructed forillustrative purposes only, and other arrangements applying many of theabove principles could be readily prepared to best suit each potentialuse scenario.

The invention claimed is:
 1. An integrated multilayer assembly for anelectronic device comprising: a first substrate film configured toaccommodate electrical features on at least a first side thereof, thefirst substrate film having the first side and a second side oppositethe first side; a second substrate film configured to accommodateelectrical features on at least a first side thereof, the secondsubstrate film having the first side and a second side opposite thefirst side, the first sides of the first and second substrate filmsbeing configured to face each other; at least one electrical feature onthe first side of the first substrate film; at least one otherelectrical feature on the first side of the second substrate film,wherein at least one of the at least one electrical feature or the atleast one other electrical feature is a mounted electronic component;and a molded plastic layer between the first and second substrate filmsat least partially embedding the electrical features on the first sidesthereof, wherein one of the at least one electrical feature on the firstsubstrate film comprises a first sensing element for detecting touch onthe assembly surface.
 2. The assembly of claim 1, wherein the firstsensing element comprises a first electrode.
 3. The assembly of claim 1,wherein one of the at least one other electrical feature on the secondsubstrate film comprises a second sensing element, the first and secondsensing elements being collectively configured to detect touch orgesture.
 4. The assembly of claim 3, wherein the second sensing elementcomprises a second electrode.
 5. The assembly of claim 1, furthercomprising at least one protective layer on at least one of the first orsecond substrate films.
 6. The assembly of claim 1, wherein at least oneof the first or second substrate films comprises a window of opticallyopaque, translucent, or transparent material having regard to apredetermined frequency or frequency band.
 7. The assembly of claim 1,wherein at least one of the first or second substrate films comprises awindow of through-hole type with no fill material.
 8. The assembly ofclaim 1, wherein the substrate film includes at least one materialselected from the group consisting of: polymer, thermoplastic material,PMMA (Polymethyl methacrylate), Poly Carbonate (PC), polyimide, acopolymer of Methyl Methacrylate and Styrene (MS resin), glass, organicmaterial, fibrous material, Polyethylene Terephthalate (PET), and metal.9. The assembly of claim 1, wherein the molded plastic layer includes atleast one material selected from the group consisting of: PC, PMMA, ABS,PET, nylon (PA, polyamide), polypropylene (PP), polystyrene (GPPS),elastomeric resin, and MS resin.
 10. The assembly of claim 1, whereinthe electrical features located on the first or second substrate filmcomprise at least one element selected from the group consisting of:conductive trace, printed conductive trace, contact pad, component,integrated circuit (chip), processing unit, memory, communication unit,transceiver, transmitter, receiver, signal processor, microcontroller,battery, light emitting device, light sensing device, photodiode,connector, electrical connector, optical connector, diode, OLED (OrganicLED), printed electronic component, sensor, force sensor, antenna,accelerometer, gyroscope, capacitive switch or sensor, electrode, sensorelectrode, printed sensor electrode, and photovoltaic cell.
 11. A methodof establishing an integrated multilayer assembly for an electronicdevice comprising: obtaining a first substrate film configured toaccommodate electrical features on at least a first side thereof, thefirst substrate film having the first side and a second side oppositethe first side; obtaining a second substrate film configured toaccommodate electrical features on at least a first side thereof, thesecond substrate film having the first side and a second side oppositethe first side; providing at least one electrical feature on the firstside of the first substrate film; providing at least one otherelectrical feature on the first side of the second substrate film,wherein at least one of the at least one electrical feature or the atleast one other electrical feature is a mounted electronic component;forming at least one of the first or second substrates into a selectedsubstantially non-planar three-dimensional shape subsequent to providingthe at least one electrical feature thereon; arranging the first andsecond substrate films in a mold so that the first sides thereof faceeach other in spaced relation; and molding a plastic layer between thefirst and second substrate films and at least partially embedding theelectrical features on the first sides thereof.
 12. The method of claim11, wherein the provision of the at least one electrical featurecomprises mounting or additively printing a first sensing element. 13.The method of claim 12, wherein the first sensing element comprises afirst electrode for sensing touch or gesture upon the assembly.
 14. Themethod of claim 13, wherein the first substrate film is configured as afront film, when in use, facing the environment and potential objects tobe sensed therein.
 15. The method of claim 12, wherein the provision ofthe at least one other electrical feature comprises mounting oradditively printing a second sensing element.
 16. The method of claim15, wherein the second sensing element comprises a second electrode forsensing touch or gesture upon the assembly in combination with the firstsensing element.
 17. The method of claim 16, wherein the first andsecond sensing elements are spatially configured to overlap in thethickness direction of the assembly.